Brassfinders: Polished Brass Round Tubing (1/2 Inch OD)
U.S. Solid 2pcs Brass Pipe Fitting Adapter, Male Pipe x Female Pipe, 1/2" x 1/
1/8 IP x 3/16", Both Ends Threaded, Fixture Stem - Lamp Pipe, Your Choice of Lengths from 1-1/2" to 36" (1/8 IP = 3/8" diameter) (22249BU) - Antique Lamp Supply - Quality Lamp Parts Since 1952
Everbilt 1/2 in. x 5 in. MIP Brass Nipple Fitting 803129 - The Home Depot
Smoking Pipe Kit in Eco Brass at Penn State Industries